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Effects of ionic strength and temperature on the aggregation and deposition of multi-walled carbon nanotubes

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Journal of Environmental Sciences 2017年第1期29卷 248-255页

作者： Lixin wang Xuezhi Yang Qi wang Yuxuan Zeng Lei ding wei Jiang Environment Research Institute Shandong UniversityJinan 250100China

The aggregation and deposition of carbon nanotubes（CNTs） determines their transport and fate in natural ***,the aggregation kinetics of humic-acid treated multi-walled carbon nanotubes（HA-MWCNTs） was investigated by time-resolved dynamic light scattering in NaCl and CaCl_2 electrolyte *** ionic strength induced HA-MWCNT aggregation due to the less negative zeta potential and the reduced electrostatic *** critical coagulation concentration（CCC） values of HA-MWCNTs were 80 mmol/L in NaCl and 1.3 mmol/L in CaCl_2 electrolyte,showing that Ca^（2＋） causes more serious aggregation than Na~＋.The aggregation behavior of HA-MWCNTs was consistent with Derjaguin-Landau-Verwey-Overbeek *** deposition kinetics of HA-MWCNTs was measured by the optical absorbance at 800 *** critical deposition concentrations for HA-MWCNT in NaCl and CaCl_2 solutions were close to the CCC values,therefore the rate of deposition cannot be increased by changing the ionic strength in the diffusion-limited aggregation *** deposition process was correlated to the aggregation since larger aggregates increased gravitational deposition and decreased random Brownian ***-MWCNTs hydrodynamic diameters were evaluated at 5,15 and 25℃.Higher temperature caused faster aggregation due to the reduced electrostatic repulsion and increased random Brownian motion and collision ***-MWCNTs aggregate faster at higher temperature in either NaCl or CaCl_2electrolyte due to the decreased electrostatic repulsion and increased random Brownian *** results suggest that CNT aggregation and deposition are two correlated processes governed by the electrolyte,and CNT transport is favored at low ionic strength and low temperature.

关键词： Carbon nanotubes Aggregation Deposition Electrolyte Temperature

Temperature Profile of Black Hole Accretion Disc with Magnetic Coupling

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Communications in Theoretical Physics 2002年第8期38卷 247-252页

作者： LEI wei-Hua wang ding-Xiong XIAO Kan Department of Physics Huazhong University of Science and Technology Wuhan 430074 China Department of Physics Huazhong University of Science and Technology Wuhan 430074 China Department of Physics Huazhong University of Science and Technology Wuhan 430074 China

Two new mapping relations between the angular coordinate on the black hole (BH) horizon and radialcoordinate on the disc are given according to the requirement of general relativity and Maxwell's equations, and theeffects of magnetic coupling (MC) on temperature of accretion disc are investigated by comparing with pure *** is shown that the MC effects on the temperature profile are related intimately to the BH spin, and the influenceon the peak value of disc temperature based on the modified mapping relations is not as great as that based on thelinear *** peak value and the corresponding radius of peak value ring of disc temperature do not increasemonotonically as the increasing spin of BH, each containing a maximum for the fast-spinning BH. The value ranges ofthe bolometric luminosity and color temperature of the disc are both extended by the MC effects.

关键词： black hole, accretion disc, magnetic coupling

A fuzzy logic cooperative MAC for MANET

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The Journal of China Universities of Posts and Telecommunications 2008年第1期15卷 55-60页

作者： wang Zhao-xiang XIA Hai-lun ding wei School of Telecommunication and Network Technology Beijing University of Posts and Telecommunications Beijing 100876 China Noah China Institute of Computing Technology Beijing 100083 China

In both wireless local area networks（WLAN） and mobile ad hoc networks（MANET）, the 1EEE 802.11e medium access control （MAC） protocol is proposed for an effective quality of service （QoS） solution. A number of studies have been done to enhance the performance of 802.11e in MANET by independently adjusting contention window （CW） size of each access category （AC） in every node. However, without the cooperation between the high priority flows and lower priority flows, the QoS goal of high priority flows cannot achieve effectively. In this article, a fuzzy logic based cooperative MAC protocol （FLCMAC） is proposed to cooperate amongst network flows and dynamically adjust access probability of each low priority flow affecting the high priority flows to satisfy their QoS requirement. The simulation results indicate that compared to the enhanced distributed channel access （EDCA） scheme of 802.11e, the FLCMAC consistently excels, in terms of throughput and delay under moderate and heavy background traffic both in single-hop and multi-hop scenarios.

关键词： 802,11e quality of service mobile Ad-hoc networks fuzzy logic cooperative MAC

High-energy-density lithium manganese iron phosphate for lithium-ion batteries: Progresses, challenges, and prospects

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Journal of Energy Chemistry 2025年第1期100卷 1-17页

作者： Bokun Zhang Xiaoyun wang Shuai wang Yan Li Libo Chen Handong Jiao Zhijing Yu Jiguo Tu State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Research Institute for Intelligent Wearable Systems The Hong Kong Polytechnic University Institute of Advanced Structure Technology Beijing Institute of Technology

The soaring demand for smart portable electronics and electric vehicles is propelling the advancements in high-energy–density lithium-ion *** manganese iron phosphate (LiMnxFe1-xPO4) has garnered significant attention as a promising positive electrode material for lithium-ion batteries due to its advantages of low cost,high safety,long cycle life,high voltage,good high-temperature performance,and high energy *** LiMnxFe1-xPO4has made significant breakthroughs in the past few decades,there are still facing great challenges in poor electronic conductivity and Li-ion diffusion,manganese dissolution affecting battery cycling performance,as well as low tap *** review systematically summarizes the reaction mechanisms,various synthesis methods,and electrochemical properties of LiMnxFe1-xPO4to analyze reaction processes accurately and guide material ***,the main challenges currently faced are concluded,and the corresponding various modification strategies are discussed to enhance the reaction kinetics and electrochemical performance of LiMnxFe1-xPO4,including multi-scale particle regulation,heteroatom doping,surface coating,as well as microscopic morphology ***,in view of the current research challenges faced by intrinsic reaction processes,kinetics,and energy storage applications,the promising research directions are *** importantly,it is expected to provide key insights into the development of high-performance and stable LiMnxFe1-xPO4materials,to achieve practical energy storage requirements.

关键词： Lithium manganese iron phosphate High energy density Lithium-ion batteries Reaction mechanism Tap density

Flexible molecules dedicate to release strain of inverted inorganic perovskite solar cell

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Journal of Energy Chemistry 2025年第1期100卷 87-93页

作者： Hongrui Sun Sanlong wang Pengyang wang Yali Liu Shanshan Qi Biao Shi Ying Zhao Xiaodan Zhang Institute of Photoelectronic Thin Film Devices and Technology Renewable Energy Conversion and Storage Center State Key Laboratory of Photovoltaic Materials and CellsNankai University Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin Haihe Laboratory of Sustainable Chemical Transformations Engineering Research Center of Thin Film Photoelectronic Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)

The tensile strain in inorganic perovskite films induced by thermal annealing is one of the primary factors contributing to the inefficiency and instability of inorganic perovskite solar cells （IPSCs）,which reduces the defect formation ***,a flexible molecule 5-maleimidovaleric acid （5-MVA） was introduced as a strain buffer to release the residual strain of *** anhydride and carboxyl groups in 5-MVA interact strongly with the uncoordinated Pb2+through Lewis acid-base reaction,thus tightly“pull”the perovskite *** in-between soft carbon chain increased the structural flexibility of CsPbI2.85Br0.15perovskite materials,which effectively relieved the intrinsic internal strain of CsPbI2.85Br0.15,resisted the corrosion of external strain,and also reduced the formation of defects such as VIand *** addition,the introduction of 5-MVA improved crystal quality,passivated residual defects,and narrowed energy level ***,power conversion efficiency （PCE） of NiOxbased inverted IPSCs increased from 19.25% to 20.82% with the open-circuit voltage enhanced from 1.164 V to 1.230 *** release of strain also improved the stability of CsPbI2.85Br0.15perovskite films and devices.

关键词： Inverted inorganic perovskite solar cells Flexible molecules Strain release Crystallization Energy barrier High PCE

A 14-year measurement of toxic elements in atmospheric particulates in Hong Kong from 1995 to 2008

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Frontiers of Environmental Science & Engineering 2014年第4期8卷 553-560页

作者： wei NIE Tao wang Aijun ding Xuehua ZHOU Wenxing wang Environment Research Institute Shandong University Jinan 250100 China Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hong Kong China Institute for Climate and Global Change Research Nanjing University Nanjing 210009 China

Toxic elements in the atmosphere can enter and accumulate in the human body, seriously impacting human health. In this study, we analyzed a 14-year （1995-2008） measurement of three toxic elements （As, Cd and Cr） in PMlo in Hong Kong, China. The pollution of these toxic elements in Hong Kong was not serious. The trend analysis showed that As and Cr in PM10 increased at a statistically significant level （p〈0.05） during the 14-year period, while the Cd in PM10 did not change significantly. Typical seasonal variations were observed for all three toxic elements, largely in relation to the Asian monsoon. Hourly 10-day backward trajectories were computed and cate- gorised into four groups. The continental air masses showed much higher concentrations of the three toxic elements than the marine air masses. The abundances of As and Cd in the PM10 were much higher in the continental air masses than those in the marine air masses, while the abundances of Cr showed an opposite pattern. The trends of the three toxic elements in East China＇s air mass were consistent with those in the overall data set ofHong Kong. Examination of the toxic element data recorded at urban sites and a roadside site also indicated a large contribution of external air masses to particulate As and Cd in Hong Kong. These results suggest that the long-range transport from the mainland of China is the dominant contributor to particulate As and Cd, while both local and long-distance sources determine the particulate Cr in Hong Kong.

关键词： toxic elements increasing trends seasonal variations air masses long-distance sources

Influence of Aspect Ratio on Giant Magnetoimpedance Effect for Fe_(67)Co_(18)Si_(11)B_4 Amorphous Ribbons

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Acta Metallurgica Sinica(English Letters) 2017年第12期30卷 1236-1242页

作者： Yan-Hong ding Ke Xue wei-Yan wang Xu Ma School of Electrical and Electronic Engineering Tianjin Key Laboratory of Film Electronic and Communication Devices Tianjin University of Technology Tianjin 300384 China School of Material Science and Engineering Tianjin University of Technology Tianjin 300384 China Tianjin Engineering Center of Near-Net-Shape Forming Technology for Metallic Materials Tianjin 300402 China

The effect of sample geometry aspect ratio （l/w） on the giant magnetoimpedance （GMI） in Fe67Co18Si11B4 amorphous ribbons was investigated systematically. The GMI profiles were measured as a function of the external magnetic field at different frequencies up to 110 MHz. The results show that there exists a critical aspect ratio （（l/w）0 = 5.4） below which the maximum GMI effect and sensitivity η decrease with decreasing l/w and above which the maximum GMI effect keeps almost constant and η decreases with increasing l/w. The observed dependence on aspect ratio as （l/w）〈（l/w）0 is correlated with the magnetization process： Complex domain structures emerged near the ribbon ends to decrease the magnetostatic energy, modify the transverse permeability and consequently GMI response. Contributions from transverse permeability and resistance may dominantly determine the change of GMI effect as （l/w）〉（l/w）0.

关键词： Amorphous Magnetic property Magnetoimpedance

MPC-based energy management with adaptive Markov-chain prediction for a dual-mode hybrid electric vehicle

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Science China(Technological Sciences) 2017年第5期60卷 737-748页

作者： XIANG ChangLe ding Feng wang weiDa HE wei QI YunLong School of Mechanical Engineering Beijing Institute of Technology Beijing 100081 China

The energy management strategy is an important part of a hybrid electrical vehicle design. It is used to improve fuel economy and to sustain a proper battery state of charge by controlling the power components while satisfying various constraints and driving demands. However, achieving an optimal control performance is challenging due to the nonlinearities of the hybrid powertrain, the time varying constraints, and the dilemma in which controller complexity and real-time capability are generally conflicting objectives. In this paper, a real-time capable cascaded control strategy is proposed for a dual-mode hybrid electric vehicle that considers nonlinearities of the system and complies with all time-varying constraints. The strategy consists of a supervisory controller based on a non-linear model predictive control （MPC） with a long sampling time interval and a coordinating controller based on linear model predictive control with a short sampling time interval to deal with different dynamics of the system. Additionally, a novel data based methodology using adaptive Markov chains to predict future load demand is introduced. The predictive future information is used to improve controller performance. The proposed strategy is implemented on a real test-bed and experimental trials using unknown driving cycles are conducted. The results demonstrate the validity of the proposed approach and show that fuel economy is significantly improved compared with other methods.

关键词： hybrid electric vehicle dual-mode energy management Markov chains model predictive control

Hierarchical porous NiO as a noble-metal-free cocatalyst for enhanced photocatalytic H_(2) production of nitrogen-deficient g-C_(3)N_(4)

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Rare Metals 2022年第2期41卷 396-405页

作者： Yu-wei Liao Jing Yang Guo-Hong wang Juan wang Kai wang Su-ding Yan College of Chemistry and Chemical Engineering Hubei Normal UniversityHuangshi 435002China Hubei Key Laboratory of Pollutant Analysis and Reuse Technology Hubei Normal UniversityHuangshi 435002China

Graphitic carbon nitride with nitrogen vacancies(NV-g-C_(3)N_(4))as a photocatalyst has been studied in solardriven energy ***,expensive and rare noble metal co-catalysts such as Pt or Pd are required in the photocatalytic H_(2)***,the exploration of low-cost and high-performance co-catalysts to replace expensive and rare noble metals has received more and more ***,a novel hierarchical porous NiO anchored on NV-g-C_(3)N_(4)is successfully *** NV-g-C_(3)N_(4)/NiO photocatalysts exhibited outstanding H_(2)evolution rate under visible light irradiation in absence of noble metal *** optimized NV-g-C_(3)N_(4)/NiO(the mass ratio of NiO is*1.7%)achieved a maximum H2 evolution rate of 170.60 lmol·g^(-1)·h^(-1),exhibiting*8.3-fold enhancement as compared to that of *** as co-catalyst provided more active sites for photocatalytic H2 ***,on the interface of NV-g-C_(3)N_(4)/NiO,an interface electric field is formed between NiO and host nitrogen-vacated g-C3N4,facilitating the transfer of the photogenerated electrons from NV-g-C_(3)N_(4)to NiO co-catalyst,resulting in significantly promoted migration and separation efficiency of the photogenerated charge carriers.

关键词： Graphitic carbon nitride Hierarchical porous NiO Photocatalysis H_(2)evolution